ABSTRACT
We are living in the information age; we need to keep information about every aspect of our lives. In other words, information is an asset that has a value like any other asset. As an asset, information needs to be secured from attacks. Since 1990, communication networks created a revolution in the use of information. Authorized people can send and receive information from a distance using communication networks. To be secure, information needs to be hidden from unauthorized access (confidentiality), protected from unauthorized change (integrity), and available to an authorized entity when it is needed (availability). Although these three requirements have not changed, they now have some new dimensions. Not only should information be confidential when it is stored in a computer, but also there should be a way to maintain its confidentiality when it is transmitted over a communication network [16].
